This car is a stock 91 305 TPI. It surges when I start it like crazy. If I come to a stop after it has warmed up it dies. I have recently tuned it up including Cap, rotor, plugs, wires, and fuel filter. Also TPS, IAC valve, MAP sensor, Ignition Module, fuel injectors (Bosch III), fuel pump, and timing. Can not find any vacuum leaks. Here are a couple videos of what it is doing. Any idea what it could be? EGR valve or solenoid?

Surging on start up
http://www.youtube.com/watch?v=SFmaz3g0AMw


Dying when warm and at idle
http://www.youtube.com/watch?v=r__GikxciTo

Driving down the road it seems to be fine. Any input is greatly appreciated. Thanks guys.

 

Any thoughts or ideas?

 

have you tried to pull the trouble codes?

 

It is not throwing codes.

 

bad ecu?

 

do you get a code 12 when you ground out the diagnostic port?

 

I am wondering about the ecu just because of no codes, and I have heard people have the same issue. I have not tried grounding the port. How do I go about that?

 

you insert a jumper in the upper 2 right hand pins in the aldl connector with the key off.
then you turn the key to ignition on but dont start it. the CEL should flash a 1 then a 2 (blink ----- blink-blink). it should do this 3 times in a row.

check this link first, it has a picture of the aldl connector and which pins to jump out

http://www.freeautomechanic.com/diag...blecodes5.html

 

I have gotten a code 12 with a faulty ecu before fyi

 

Awesome info! Thanks for the advice. I can't get to it til tomorrow but I will check it then.

 

is there a better way to tell? im having a problem myself with the est circuit and id like to be able to rule out an ecm.

 

Also, it seems to idle better with my coolant temp sensor unplugged, and that throws a code of course.

 

Keep us posted. I have the same exact problem with the same exact car/engine. I have also replaced everything you replaced with no luck.

I have not replaced fuel filter, ECU, or alternator. Perhaps the problem lies there. Did you replace the fuel filter when you replaced the pump? I assume you positioned the TPS correctly with a volt meter and made sure the IAC was set to the correct length? I did, and it didn't help...

One thing I can suggest is to increase the idle speed with the idle screw. Idles higher when warm and won't die as often...but it still surges. I'm going to be replacing my Air Diverter valve this weekend. i'll let you know if that helps. If that doesn't work I'm going to find a shop that can run a diagnostics on the car. Problem is most shops have never seen a TPI system this old and they are clueless about it.

 

I had a buddy who is a mechanic do the tps and IAC for me and adjust them. I did the fuel filter the day after the pump, so same time frame. I keep reading about people with this same issue and have not seen anyone post a clear fix that they had. Fingers crossed.

 

I found out I had a bad ecu when it was hooked up to a computer and giving a temp of -12 degrees for the engine. I had recently replaced the sender so I knew that was good. I was told when it reads like that it was usually the ecu, after it was replaced car ran perfect.

 

I'm gonna try replacing the ECU like ConlinJ suggested. Where did you get the ECU? How much? How do I know which one to buy?

 

There are only two tpi ecu's 7165 and 730 your car should use the 730. Before you replace the ecu try to have yours read on a scanner and test read the values the sensors are returning. ECU's aren't cheap if you get them from a store, make sure you need to replace it first. I got my ecu years ago when i had a friend at A-1 Cardone.

 

http://cgi.ebay.com/ebaymotors/1990-...mZ320449995833

 

I want to beat my head into a wall. My car will not throw codes, but will not idle for crap. I have had 3 mechanics look at it and they are stumped, so I am pissing money away there. I ordered a re-manufactured ecu and installed it because everyone I talk to said that is it. Installed it and same issue, but as I drove it around to get up to temp, I was going up a hill and it lost all throttle and died. Now it will not start. I have not put the old ecu back in yet, but I am pulling my hair out here.

 

I am going to go and try the old one now, see what happens.

 

Put the old one back in and fired right up, ran like it did before. Guess the new ecu is bad.

 

Have you checked for any vacuum leaks? did you put a fuel pressure gauge on it and watch what the car it's doing while idling, driving?

 

No leaks. Fuel pressure was tested at a shop and was fine.

 

How did you check for leaks? Did you watch the fuel pressure under load? Also have you checked the regulator itself I didn't see that mentioned.

-Jim

 

Also when you replaced the tps and iac did you set the minimum air?

 

I as well as a mechanic checked for leaks. The only leak I had was in the break booster line, and was fixed. I have not checked the fuel pressure regulator, but the fuel pressure was check at idle and load and was fine. It was checked after I swapped the injectors, and by a mechanic as well. I will check the minimum air tonight. Not sure if he did that, though he did set the TPS and IAC for sure. I checked the TPS last night again and got 0.56, and went to 4.27 on throttle, so that is well within the good range.

 

Question. It says to warm engine up to operating temp when adjusting idle for minimum air, but when I am at operating temp it dies when idling. Is this going to work for me with this issue? Any tips?

 

When you were checking for leaks did you spray around the tpi gaskets with carb cleanerand listen for the idle to change?

 

I did not because I had installed all new gaskets because I had just done the injectors. I will check that next. I adjusted the minimum air tonight. It was lower than it should be, but it is still surging. It was never adjusted before because I had to knock the cover out. I adjusted it up a little higher than it should be, but now it does not die like it was due to higher idle.

 

Changed the ECU tonight with the new one they sent me and car is idling like a champ!

 

Glad to hear!

 

me too! I was ready to scream.

 

Thanks for posting and glad to hear you solved the problem. I am having the same problem and have checked all the things you mentioned except the computer. Now I will look into that.

 

I wanted to make sure I posted my fix because there are literally dozens of threads on this issue and no one really posts the fix that worked for them. Probably different for everyone, but too many damn things on these engines cause the same symptoms.

 

After I installed the ecu I readjusted my minimum air and tps. Probably a good idea to do that as well if yours is the ecu.

 

Did you get the ECU from that EBAY add you posted? I assume you just swapped your old PROM..?

I replaced my MAP sensor (again) as I was getting a code 33 and mine is running a lot better now. I'm still thinking about a new ECU as it looks like it fixed your problems. Thanks for keeping the thread going.

 

I did order from the link above. I got one and it did not work. I wrote the seller and the sent me another one, and I got it the next day. Very easy to deal with,and stood behind their product. The company is http://www.siaelec.com/ that it came from. A lot cheaper through their eBay page than online at their site.

 

I hear you... I started a thread as well and will make sure to post once I figure out what the problem is.